/*
 * Copyright 2011,2012 Metamarkets Group Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package sg.atom.utils._beta.functional;

import com.google.common.base.Function;
import com.google.common.base.Predicate;
import com.google.common.base.Predicates;
import com.google.common.collect.Iterables;
//import com.metamx.common.guava.nary.BinaryFn;
//import com.metamx.common.guava.nary.BinaryTransformIterable;
//import com.metamx.common.guava.nary.TrinaryFn;
//import com.metamx.common.guava.nary.TrinaryTransformIterable;

import java.util.Iterator;

/**
 */
public class FunctionalIterable<T> implements Iterable<T> {

    private final Iterable<T> delegate;

    public static <T> FunctionalIterable<T> create(Iterable<T> delegate) {
        return new FunctionalIterable<T>(delegate);
    }

    public static <T> FunctionalIterable<T> fromConcatenation(Iterable<T>... delegates) {
        return new FunctionalIterable<T>(Iterables.concat(delegates));
    }

    public static <T> FunctionalIterable<T> fromConcatenation(Iterable<Iterable<T>> delegates) {
        return new FunctionalIterable<T>(Iterables.concat(delegates));
    }

    public FunctionalIterable(
            Iterable<T> delegate) {
        this.delegate = delegate;
    }

    public Iterator<T> iterator() {
        return delegate.iterator();
    }

    public <RetType> FunctionalIterable<RetType> transform(Function<T, RetType> fn) {
        return new FunctionalIterable<RetType>(Iterables.transform(delegate, fn));
    }

    public <RetType> FunctionalIterable<RetType> transformCat(Function<T, Iterable<RetType>> fn) {
        return new FunctionalIterable<RetType>(Iterables.concat(Iterables.transform(delegate, fn)));
    }

    public <RetType> FunctionalIterable<RetType> keep(Function<T, RetType> fn) {
        return new FunctionalIterable<RetType>(Iterables.filter(Iterables.transform(delegate, fn), Predicates.notNull()));
    }

    public FunctionalIterable<T> filter(Predicate<T> pred) {
        return new FunctionalIterable<T>(Iterables.filter(delegate, pred));
    }

    public FunctionalIterable<T> drop(int numToDrop) {
        //return new FunctionalIterable<T>(new DroppingIterable<T>(delegate, numToDrop));
        return null;
    }

    public FunctionalIterable<T> limit(int limit) {
        return new FunctionalIterable<T>(Iterables.limit(delegate, limit));
    }

    public FunctionalIterable<T> concat(Iterable<T>... toConcat) {
        if (toConcat.length == 1) {
            return new FunctionalIterable<T>(Iterables.concat(delegate, toConcat[0]));
        }
        return new FunctionalIterable<T>(Iterables.concat(delegate, Iterables.concat(toConcat)));
    }

    public FunctionalIterable<T> concat(Iterable<Iterable<T>> toConcat) {
        return new FunctionalIterable<T>(Iterables.concat(delegate, Iterables.concat(toConcat)));
    }
//    public <InType, RetType> FunctionalIterable<RetType> binaryTransform(
//            final Iterable<InType> otherIterable, final BinaryFn<T, InType, RetType> binaryFn) {
//        return new FunctionalIterable<RetType>(BinaryTransformIterable.create(delegate, otherIterable, binaryFn));
//    }
//
//    public <InType1, InType2, RetType> FunctionalIterable<RetType> trinaryTransform(
//            final Iterable<InType1> iterable1,
//            final Iterable<InType2> iterable2,
//            final TrinaryFn<T, InType1, InType2, RetType> trinaryFn) {
//        return new FunctionalIterable<RetType>(TrinaryTransformIterable.create(delegate, iterable1, iterable2, trinaryFn));
//    }
}
